The width of a tracker is 67.3 and a blazer is 67.7 but would the mounts be the same. Could I fit an off road bumper from a 2002 tracker on to a 2002 blazer ??

 

I'd be surprised if the frame mounts were the same, but looks like the size is approximately the same. The Tracker is a re-badged Suzuki. Totally different beast from the Blazers. That being said, a little fabrication adaptation on the mounts could make it work for you. If you has some skill welding, or know someone who does I'd say go for it. I think that bumper would look great on a Blazer.